Which Genetic Tests are Really Worth Getting?

With Congress poised to eliminate a big barrier to genetic testing for risk of certain diseases, consumers still face challenges in figuring out which ones offer useful information.

Despite heavy marketing by some genetic-test makers, the wide use of genetic tests has been held back by a variety of factors, including questions about the tests' usefulness and concerns that results could be used by employers and insurers to discriminate against people. Critics argue that many tests can't accurately identify which people are at risk for various illnesses.

But genetic researchers say that certain genetic tests are valuable because they do tie closely to particular medical conditions and patients can help their health by acting on the tests' findings.

Among tests that have broad support among doctors are a breast- and ovarian-cancer test that looks at genes known as BRCA1 and BRCA2, and a colon-cancer test that examines three genes linked to a form of the disease known as hereditary nonpolyposis colorectal cancer, or HNPCC. The tests are generally given only to patients who, due to family history and other factors, appear likely to carry the problematic genes.

Kenneth Offit, chief of the clinical genetics service at Memorial Sloan-Kettering Cancer Center in New York, says that when these tests signal a genetic risk, patients can take action. In the case of the breast-cancer test, for instance, he recommends that patients get yearly magnetic resonance imaging scans starting at the age of 25, rather than relying on typical mammograms that often start in the mid-30s. If the colon-cancer test results show a danger, he urges patients to begin annual colonoscopies at 25, rather than the typical practice of having a first one at 50.

Gene tests associated with a number of relatively rare diseases have also won general acceptance. One detects a condition called factor V Leiden, which is associated with an elevated risk of blood clots. Brian F. Gage, an associate professor at Washington University in St. Louis, suggests the test for women with a strong family history of clotting problems who are considering taking birth-control pills, which also carry a clotting danger. If a woman does have the risky genetic variant, he would urge her to consider different contraception.

•	Which Genetic Tests are Really Worth Getting? The Wall Street Journal, Thursday, May 1, 2008 Byline: Anna Wilde Mathews